Andrea Leadsom, a candidate to succeed David Cameron as British prime minister, speaks at a news conference in central London, Britain July 4, 2016. REUTERS/Peter Nicholls

Former London Mayor Boris Johnson has given his backing to junior minister Andrea Leadsom in the Conservative Party leadership contest, according to media reports, including from the Press Association.

Johnson, a leading Brexit campaigner, ruled out making his own bid to replace David Cameron as Conservative leader as Britain’s Prime Minister last Thursday.

His decision not to stand came after Justice Secretary Michael Gove, a fellow “Leave” campaigner, said he would be a candidate. Gove had previously said he would back Johnson.

Leadsom and Gove are competing against interior minister Theresa May, work and pensions minister Stephen Crabb and former defence minister Liam Fox for the position.